Rotating cutting tool

ABSTRACT

A rotatable milling cutter having a plurality of helically extending teeth each of which has a cutting face side and a trailing side interconnected by a relieved surface which extends at an acute angle to a tangent line which extends through a cutting edge defined by the intersection of the cutting face side and the relieved surface. Wall means are provided on the cutting face side of the teeth which define a plurality of generally axially spaced pockets or indentations recessed from the cutting face side toward the trailing side. This construction presents a cutting edge which when geometrically developed is a generally regularly shaped reoccurring curve which has a large pitch with respect to amplitude and this cutting edge is the edge which is presented to the work which the cutter operates upon. The construction of the present invention also includes the provision of flattening the high point or high area of a portion of the above referred to reoccuring curve and the flattened portion is designed to be generally parallel to the axis of the tool. The present construction also improves the strength characteristics of the teeth at their extreme end faces.

United States Patent [1 1 Ribich ROTATING CUTTING TOOL [75] Inventor:Thomas A. Ribich, Cleveland, Ohio [73] Assignee: The Weldon ToolCompany,

Cleveland, Ohio [22] Filed: Dec. 14, 1972 [21] App]. No.: 315,021

Related US. Application Data [63] Continuation of Ser. No. l74,058, Aug.23, 1971, abandoned, which is a continuation-in-part of Ser. No. 31,594,April 24, l970, abandoned, which is a continuation-in-part of Ser. No.822,971, May 8, 1969, abandoned.

Primary Examiner-Harrison L. Hinson Attorney-Woodling, Krost, Granger &Rust 1 Dec. 4, 1973 [5 7 ABSTRACT A rotatable milling cutter having aplurality of helically extending teeth each of which has a cutting faceside and a trailing side interconnected by a relieved surface whichextends at an acute angle to a tangent line which extends through acutting edge defined by the intersection of the cutting face side andthe relieved surface. Wall means are provided on the cutting face sideof the teeth which define a plurality of generally axially spacedpockets or indentations recessed from the cutting face side toward thetrailing side. This construction presents a cutting edge which whengeometrically developed is a generally regularly shaped reoccurringcurve which has a large pitch with respect to amplitude and this cuttingedge is the edge which is presented to the work which the cutteroperates upon. The construction of the present invention also includesthe provision of flattening the high point or high area of a portion ofthe abovereferred to reoccuring curve and the flattened portion isdesigned to be generally parallel to the axis of the tool. The presentconstruction also improves the strength characteristics of the teeth attheir extreme end faces.

31 Claims, 19 Drawing Figures PMENTEBBEE 915 sum 10? o INVENTOR.

THOMAS A. RIB/Ch 000% M m kfi PATENTEUUEC M973 3.775.819

SHEET 20E 6 Fla 8 INVENTOR.

THOMAS A. RIB/CH Unfit Gib PATENIEUHEB 41915 37753319 SHEET 30F 6 INVOR.

THOMAS A. CH

@339 wk m UK a PATENTEDHEC 4 ms 3.775819 SHEET 5 0F 6 INVENTOR.

THOMAS A. RIB/Ch 1 ROTATING CUTTING TOOL This application is acontinuation application'of'U. S. Pat. application Ser. No. 174,058filed Aug. 23, 11971, and entitled Rotating Cutting-Tool, which in turnwas acontinuation-in-part application of U. 8. Pat. application Ser. No.31,594, filed Apr. 24, 1970, and entitled Rotating Cutting Too which inturn was-a cont-inuation-in-part application of U. 8. Pat. applicationSer. No. 822,971 filed May 8, 1969 and'entitled Rotating Cutting Tool,-all now abandoned.

u. s. Pat. No. 3,133,339 issued May 19, 11964 is an example of the priorart on this subject, however, the basic problem involved in thisconstruction-is not in the finished tool, which functions in theadvantageous manner pointed out in this patent, but rather in thedifficulties involved in producing (initially and in freshar'pening) thecutting edges on the tool. The cutting edge on this type of tool isproduced by holding the tool in a relatively sophisticated andrelatively expensive fixture which appropriately moves the tool,andrnore s'pecifically the cuttingedge thereof; relative to a grindingwheel. This produces the generally wavy shaped'cuttiiig" edge disclosedin U. S. Pat. No. 3,133,339.

Commercial users of this tool and particularly small machine shops,usually find it financially advantageous to ship these tools back to theproducer for resharpening, rather than expend money for the purchase ofthe aforementioned fixtures, This results in delay and other inherentdisadvantages to the user of the tool.

It is therefore an object of this invention to providea rotating cuttingtool having acutting edge-of the type discussed hereinabove whichcutting edge can be provided on the tool by relatively inexpensiveequipment normally possessed by small establishments.

Anotherobject of this invention is to provide such an improved toolwherein the generally wavy shaped cut ting edge can be convenientlyremoved by conventional sharpening methods to produce the conventionalcutting edge on such tools (such as end mills, etc.)

wherein substantially all points on the cutting edge lie on a constantradius from the center line of the tool.

Another object of this invention is to provide a flat or substantiallyflat surface onthe high areas of the wavy shaped cutting edge ofthe'tool whichflat portions are parallel to the tool axis and whichwillproduce a substantially flat surface on a workpiece upon which itperforms its intended function while-stillmaintaining the chipbreakingeffect of the wavy edge.

Other objects and a fuller understanding of this irivention may be hadbyreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is an elevational view of a tool constructed under the teachingsof the present invention;

FIG. 2 is an enlarged view taken generally. along the line2-2 of FIG. 1;

FIG. 3 is astill further enlarged fragmentary isometric view ofthecutting end portion of the tool showitin FIG. 1;

IGS. 4, Sand 6 are views taken along the respective lines 4-4, 5-5 and66-of FIG. 3

" FIG. 7 is a somewhatschem'a'tic view (taken'in the same direction asFIG. 1') of one of :the teeth'of the tool' line 8 -8 FIG. 9 is a viewsimilar to FIG. 4 but showing the tool prior to the relief surface beingground on the tooth;

on a substantially constant radius with respect to the axis of the tool;

'FIG. 11 is 'a sectional view taken generally along the line ll--l l ofFIG. demonstrating generally the cross sectional appearance of thereground cutting edge shown in FIG. 10;

FIG. 12 is an elevational view of a modification of the tool shown inFIG. 1 and constructed under the teachings of the present invention;

FIG. 13 is an enlarged fragmentary isometric view of a portion of thetool shownin FIG. 12;

FIG. 14 is a somewhat schematic view similar to FIG. 7 showing one ofthe teeth of the tool shown in FIG. 12 and taken in a direction which isgenerally radial with respect to the axis of the tool; I

FIG. l5 is a view taken generally along the line 1515 of FIG. 14;

FIG. 16 is a representation of the cutting edges on each of the fourteeth of the tool shown in FIG. 12 and showing the axial offset of thehigh and low areas of each of the cutting edges with respect to eachother;

FIG. 17 is an elevational view of a modification of the tools shown inFIGS. 1 and 12 and constructed under the teachings of the presentinvention;

FIG. is is an end view of the tool shown in FIG. 17 looking in thedirection of the arrows 18 18 of FIG. 17; and

FIG. 19 is a development of the six teeth shown on the tool of FIGS. 17and 18.

The preferred embodiment of the present invention will be demonstratedand described in connection with an end mill indicated generally by thereference numetal 20 and it will be readily appreciated by. thoseskilled in the art that the invention is readily adapted to rotatingtools generally designated as milling cutters. The end-mill 20 has animproved cutting action as described hereinabove and as seen, includesin combination' a shank end portion 23 and a cutting end portion 25 andthese two portions are produced from one integral piece of metal as isconventional in the art. The cutting end portion 25 comprises aplurality of teeth specifically four in number in the presentembodiment,

and these teeth have been identified by the reference tween and connectsthe sides 34 and 36. The intersection of the cutting face side 34 andthe land surface 38 comprises and forms the cutting edge 40 of the endmill;

In the conventional design of the straight sided end mill; the cuttingedges extend in the helical direction around the axis of the tool withthe cutting edges being generally on a substantially constant radiuswith respect to the axis of the tool. It is true of course that in thisart there are what are commonly referred to as tapered end mills whereinthe cutting edge of each tooth has a constantly increasing radius withrespect to the axis of the tool as the edge extends from the point ofthe tool to the shank end portion. However, even in this type tool,corresponding portions of each of the cutting edges are on the sameradius which increases in a constant manner from the point of the tooltoward the shank end. It will also be appreciated by those skilled inthe art that there are such things as straight-fluted tools of this typewherein the teeth do not extend in the helical direction, but extend ina manner parallel to the axis of the tool. All of these enumerated typesof tools are susceptible of being constructed in accordance with theteachings of the present invention.

FIG. 7 is a somewhat schematic illustration of one of the teeth 29 takenin the same direction as FIG. 1 and the conventional configuration ofthe tooth would be that defined between the line 36 representing thetrailing side and the dot-dash line 42. The axis of the tool 20 isindicated by the reference numeral 43. The present invention includesthe provision of wall means on the cutting face side of each of theteeth which defines a plurality of axially spaced indentations 45 whichas noted are recessed toward the trailing side 36 (from line 42) wherebythe cutting edge 40 when viewed in the generally radial direction of theend mill(FIG. 7) defines a curve with high areas 47 and low areas 49with the low areas being closer to the trailing side 36. Another way ofdescribing the curve in this particular embodiment is to refer to it asa smooth and continuous curve somewhat on the order of or approaching asine wave in configuration. The indentations 45 are produced by metalremoval from the conventional tooth configuration by appropriatelymoving an end mill and the present tool relative to each other.

FIGS. 4, and 6 are views taken along corresponding positions of the land29 in FIG. 3 and show the cross sectional design of the tooth at spacedaxial positions. The previously identified land surface 38 is seen inFIG. 4 and shows thereon the lowest point on the cutting edge 40 whichis identified by the reference numeral 51. This point 51 is located onone of the low areas 49 previously discussed which is produced as aresult of one of the indentations 45. One of the highest points on thecutting edge 40 is also seen in this view and has been identified by thereference numeral 53. It will therefore be observed from this view thatthe point 51 is located on a smaller radius with respect to the axis ofthe tool than is point 53. There is therefore produced, as viewed in thedirection of the arrow 55 in FIGS. 4, 5 and 6, a series of highs andlows interconnected by intermediate points to present a cutting edge 40as seen in FIG. 8. This is the cutting edge which presents itself to thework upon which it is to perform its intended function. The Y distancein FIG. 6 is the amplitude dimension shown in FIG. 8.

It will therefore be apparent with the design shown in FIGS. 4, 5 and 6,that when the cutting edge 40 be comes dull, all that need be done is toregrind the land surface 38 as shown in FIGS. 4, 5 and 6 in aconventional manner to resharpen edge 40.

FIG. 9 is a view similar to FIG. 4 but showing the and mill blank withthe indentations 45 but before the relieved land surface 38 has beenproduced thereon. It will therefore be seen in this configuration thatthe land surface 38 now identified as 58, extends as the surface of acylinder whose radius extends from this surface to the center line ofthe tool. In this construction a point 63 which corresponds to point 53in FIG. 4, and a point 61 which corresponds to point 51 in FIG. 4, areboth seen to lie on the circumference of this hereinabove describedcylinder. By grinding the relieved land surface 38 on this blank, theconstruction of FIG. 9 is converted to that shown in FIGS. 4, 5 and 6.The blank of FIG. 9 can also be converted to the construction of FIGS.10 and 11. The blank has utility and invention as well as theconstruction of FIGS. 1 through 8.

FIGS. 10 and 11 Show the construction of the tool of the presentinvention when it is desired to produce a cutting edge which isconventional in nature in that the edge and substantially all pointsthereon lie on a constant radius from the center of the tool. In orderto accomplish this end result it is necessary to regrind the tool in amanner known to those skilled in the art so as to remove the high pointsand the low points identified by the numerals 51 and 53 in FIGS. 4, Sand6 so that these points now lie on the same radius with respect to thecenter line of the tool. These points are identified by the referencenumerals 71 and 73 in FIG. 10. The design of this construction isprovided with a primary relief land surface 78 and secondary relief landsurface 88 with the surface 88 making a greater angle with a tangentwhich extends through points 71 and 73 than does surface 78.

In the original blank as it is herein referred to as shown in FIG. 9, itwill be seen that the land surface 58 is formed as the arc of a circleand the land surface 78 which is finally ground onto the land extendsgenerally as a chord or a portion of a chord of this circle.

As a result of the present construction, it will be seen by thoseskilled in the art that the shape of the cutting edge 40 which ispresented to the work and as seen in FIG. 8, is readily and economicallyproduced utilizing conventional grinding methods when resorting to theteachings of the present invention. The cutting edge so produced hasmany advantages in that continuous and discontinuous moon shaped chipscan be produced and it will be noted that entire length of a cuttingedge is not presented to the work at one time thereby giving longer lifeand better cutting action to the tool. Another problem which is solvedby the cutting edge of the present invention is that in slottingoperations performed by conventional end mills, it has long been theproblem that the end mill has a tendency to walk to one side or theother of the intended extent of the slot because of the inherent pullingpower of the cutting edge depending on whether the tool is right or lefthanded. It will be seen that the cutting edge of the present inventionis continuously passing from a lefthanded to a right-handed direction asit goes through the high and low points on the cutting edge curve. As aresult it appears that the present cutting edge design has the inherentcapability of avoiding the inherent problems, for example, in slottingoperations encountered by conventional end mill designs. The otheradvantages initially pointed out in the specification are alsoaccomplished by the present specification.

The high and the low points on the cutting edges of the other teeth 29,30 and 31 are placed out of phase with each other so as to provide acontinuous and consistent cutting operation as the tool rotates andmoves in a feed direction relative to a workpiece. In other words, thecutting edge 40 seen in FIG. 8 on flute 29 has a series of high areas orpoints axially spaced from each other and the distance between thesehigh points is known as the pitch. The high points on edges 40 on teeth28, 30 and 31 are axially offset with respect to each other and withrespect to tooth 29. For the sake of example if the pitch of the highpoints on edge 40 of tooth 29 is one-fourth inch, then correspondinghigh points on teeth 28, 30 and 31 are progressively spaced apartone-sixteenth inch. This produces a spacing of one-sixteenth inchbetween adjacent high points.

The tool of the present invention which is illustrated in FIGS. 12through 16 will be identified by the same reference numerals utilized indescribing the tool of FIGS. 1 through 8 and different referencenumerals will be utilized only in describing those specifc changes whichhave been incorporated into the modified tool. Since there arestructural changes in the tool of FIGS. 12 through 16 over thepreviously described tool, the tool in general will be identified by thereference numeral 120. The change in construction comes about in theindentations or pockets 145 which are produced by metal removal from theconventional tooth configuration by the appropriate movement of an endmill relative to the end mill blank. This is best observed by referringspecifically to FIGS. 14 and 15. FIG. 14 is taken in what may bereferred to as a radial direction of the tool shown in FIG. 12. The axisof the tool, however, has been shifted approximately 90. As seen in FIG.14, the pockets or indentations 145 are produced by a metal removal tooland these pockets or indentations are axially spaced in a manner similarto that shown in FIG. 7. The pockets are produced in such a manner as torecess the cutting face side 34 of the tooth toward the trailing side36. The difference in FIG. 14 from FIG. 7 is brought about by theslightly different movement of the metal removing tool. The cutting edge140, which is produced as seen in FIGS. 14, 15 and 16 differs becausethe metal removing tool is maneuvered in a slightly different directionwhen producing the high areas 147 as distinguished from the low areas149. It will be seen that the tool is maneuvered so as to produce flatportions or surfaces 150 on the top of the high areas.

FIG. 15 is a view taken generally along the line 15l5 of FIG. 14 and itwill be noted that when the high areas 147 of the cutting edge 140 areflattened, that the high areas 147 as viewed in the direction of FIG. 15are also flattened. The direction of the view of FIG. 15 is basicallythe direction which the cutting edge occupies as it approaches aworkpiece upon which it is to accomplish its intended function. It willthus be seen that as a given cutting edge 140 makes a pass through theworkpiece, it will produce a cutting effect upon the workpiece which hasa surface which is complementary to the flat surface 150 of the cuttingedge. A portion of the remainder of the cutting edge 140 as it proceedsfrom the high area 147 to the low area 149 will produce a cutting effectwhich will also be complementary to the rest of the curve of the cuttingedge depending upon the feed rate at which the tool is being fed intothe workpiece.

FIG. 16 is a representation of the axial position of the high areas andlow areas 147 and 149 on each of the cutting edges 140 on the teeth 28,29, 30 and 31.' As will be seen in FIG. 16, there are shown teeth 28,29, 30 and 31, and it will be seen that the high areas and low areas oneach of the curves are offset axially with respect to each other. Itwill be specifically noted that the flat surfaces 150 of the cuttingedges on each of the teeth is progressively axially offset with respectto an adjacent cutting edge so that the tool, as it makes a cutting passthrough a workpiece will produce a finished surface which iscomplementary to the flat surfaces 150. By overlapping the flat surfaceson adjacent cutting edges, there is produced a continuous finishedsurface in an axial direction which is parallel to the axis of the tool.The advantage of this particular construction over the tool shown inFIGS. 1 through 8 is that many times the tolerance specification for thefinished surface is too close to be produced by the tool of FIGS. 1through 8 (to produce an acceptable finish) because of the variations inthe high areas 47 as compared to the low areas 49 as viewed in FIG. 8.The design, best shown in FIGS. 14, 15 and 16, therefore produces afinished surface on the workpiece which does not have the variationstherein produced by the curved high areas 47 as seen in FIGS. 7 and 8but rather has a finished surface which is parallel to the axis of thecutting tool because of the flat surfaces which are designed into thehigh areas 147. The tool therefore has the inherent advantages of beingable to break up chips, yet which can function to produce a finishedsurface which is parallel to the axis of the cutting tool. Additionally,the device of FIGS. 12 through 16 can be utilized to produce acontinuous chip if desired depending upon the rate at which the tool isfed into the workpiece. The pitch distance of adjacent high areas 147 isindicated by P in FIG. 16 and it will be seen that the axial distance ofa flat surface 150 multiplied by the number of cutting edges (four inthis case) is at least as great as the pitch distance so that acontinuous and uninterrupted smooth surface is produced on theworkpiece. As seen from FIG. 16 the flat surfaces on edges 140 of teeth29, 30 and 31 will cut or machine any material missed by thelow area 149on edge 140 of tooth 28. The curve defined by the cutting edge 40 inFIGS. 6 and 7 can be referred to as generally sinusoidal.

It will be noted from a review of the drawings and description of theinvention hereinabove and particularly FIGS. 1, 2, 3, 12 and 13, thatthe teeth (for example, 28, 29, 30 and 31) at their extreme end faceshave varying physical size and as a result, the forward end portions ofthe teeth have varying strength characteristics. This results from thefact that the indentations (45 or 145 in FIGS. 7 and 14, respectively)on adjacent teeth are axially offset with respect to each other and theextreme end of a tooth may fall either in the low part of an indentationor on the high point thereof or in between the two. As the indentationsare out of phase with each other, the distances from the lastindentation of each tooth to the forward end thereof vary from tooth totooth. This results in a lack of uniformity in strength characteristicsof the several teeth at the forward end face of the tool.

FIGS. 17, 18 and 19 illustrate an end mill which has a constructionwhich obviates the immediately above mentioned difficulties andstructural deficiencies. This construction and feature is alsoapplicable to all of the embodiments of the invention which are shown inFIGS. 1-16. For simplicity in illustration, this construction or featureis shown as applied only to FIGS. 17, 18 and 19.

The end mill 160 includes a shank end portion 163 and a cutting endportion 165 which includes, by way of example, six teeth 168, 169, 170,171, 172 and 173. These teeth, as in the other embodiments, have acutting face side which has a constant positive radial rake angle orrelationship with respect to the tool axis. This relationship is bestillustrated and seen in FIGS. 4 through 6. FIG. 19, which is adevelopment of the six teeth on the tool of FIGS. 17 and 18, best showsthe discussed inventive concept of this modification. The respectiveteeth 168-173 are provided with helically extending forward end portions176-181 which do not include pockets or indentations (like 45 or 145 inFIGS. 7 and 14, respectively) but extend on a constant helix for a givenaxial distance from the extreme end of the tool. It will be seen thatend portion 176 of tooth 168 is the shortest portion with respective endportions 177, 178, 179,180 and 181 of succeeding teeth beingsuccessively longer than end portion 176. These lengths are dictated bythe offset between respective indentations, (all of which indentationshave been identified by the reference numeral 185) and the number ofteeth on the tool. The indentations 185 are identical with indentations45 and 145, and the cutting face and edges on teeth 168-173, are thesame as, those appearing on the tools of FIGS. 1-1 1 from the firstindentation 185 at the forward end of the tool back to the shank endportion 163. The cutting face and edges on portions 176181 are best seenin the end view of FIG. 18.

The axial length of portion 176, or in other words the shortest lengthof conventional tooth helix, has been found to be ideally one-eighth ofthe maximum outside diameter (O.D.) of the cutting end portion of thetool. This means that if the CD. at the cutting edges is lrinches, theaxial length of portion 176 should be preferably on the order ofthree-sixteenth inch. It has been found, however, that preferably thelength of portion 176 may lie in the range of from one-sixteenth toonefourth the CD. of the cutting end portion 165, with the mostpreferred at said ratio of one-eighth. It will thus be seen from FIG. 17and the end view of FIG. 18 that the portions of all of the teeth 168through 173 at their extreme forward ends of the cutting tool are all ofthe same physical character and strength and with variations ofconstruction in the several teeth adjacent the forward end portionminimized.

This particular construction simplifies the addition of a chamfer 187(FIG. 18) to remove the sharp termination of each of the peripheralcutting edges where they meet the end teeth. The same is true when comercutting radii are required due to workpiece specifications. Thisconstruction is also advantageous when performing axial gashingoperations on the extreme end of tools, especially the end centercutting chip breaker type.

As mentioned hereinabove, all of the embodiments of the tools show andillustrate that the cutting face side of each tooth has a constantpositive radial rake angle or relationship with respect to the toolaxis. This terminology is well understood by those skilled in the art.However, it might be further explained by saying that the rake ispositive if a tooth cutting face surface trails its cutting edge inrotation or when a tooth cutting face surface lies on a radial linewhich, if extended toward the tool axis would pass behind the axis inrespect to the cutting direction of rotation.

Although this invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

1. A milling cutter blank having an axis and including in combination acutting portion, said cutting portion comprising a plurality of teeth,each said tooth having a cutting face side, a trailing side, and a landsurface connecting the two aforementioned sides, said cutting face sidehaving a constant positive radial rake relationship with the cutteraxis, wall means on said cutting face side of said tooth defining aplurality of axially spaced indentations which are recessed toward saidtrailing side from a reference line at said cutting face side which lineextends generally parallel to said tooth.

2. A milling cutter blank as claimed in claim 1, wherein said axiallyspaced indentations on said cutting face side of said tooth start at agiven spaced axial distance from the extreme forward axial end of saidtooth with said tooth for said given spaced axial distance being ofconventional unindented construction, said given spaced axial distancebeing on the order of at least one-sixteenth of the outside diameter ofsaid cutting portion.

3. A milling cutter blank as claimed in claim 2, wherein said givenspaced axial distance is on the order of at least one-eighth the outsidediameter of said cutting portion.

4. A milling cutter blank as claimed in claim 1, wherein said teethextend in a helical direction at a given helix angle.

5. A milling cutter blank as claimed in claim 1, wherein said landsurface is formed as an arc of a circle.

6. A milling cutter blank as claimed in claim 4, wherein said cutterblank is an end mill blank with a shank end portion connected to saidcutting portion.

7. A milling cutter having an axis and having an improved cutting actionincluding in combination a cutting portion, said cutting portioncomprising a plurality of teeth extending in generally an axialdirection, each said tooth having a cutting face side, a trailing side,and a land surface connecting the two aforementioned sides, said cuttingface side having a constant positive radial rake relationship with thecutter axis, the intersection of said cutting face side and said landsurface defining a cutting edge which is continuous substantially theentire axial length of said tooth, said land surface being relieved fromsaid cutting face side in the direction of said trailing side, wallmeans on said cutting face side of said tooth defining a plurality ofaxially spaced indentations which are recessed toward said trailingside.

8. A milling cutter as claimed in claim 7, wherein said wall means whichdefine said plurality of axially spaced indentations also define aplurality of axially spaced high areas and low areas when viewed in theradial direction of the milling cutter.

9. A milling cutter as claimed in claim 8, wherein said cutting edgewhen viewed in a direction generally at a right angle to said radialdirection defines a plurality of connected curves having alternatelyhigh areas and low areas.

10. A milling cutter as claimed in claim 9, wherein said last mentionedhigh areas are generally flat on top.

11. A milling cutter as claimed in claim 8, wherein said cutting edgewhen viewed in a direction generally at a right 'angle to said radialdirection defines substantially a straight line.

12. A milling cutter as claimed in claim 7, wherein said axially spacedindentations on said cutting face side of said tooth start at a givenspaced axial distance from the extreme axial forward end of said toothwith said tooth for said given spaced axial distance being ofconventional nonindented construction, said given spaced axial distancebeing on the order of at least onesixteenth of the outside diameter ofsaid cutting portion.

13. A milling cutter as claimed in claim 12, wherein said given spacedaxial distance is on the order of at least one-eighth of the outsidediameter of said cutting portion.

14. An end mill having an axis and having an improved cutting actionincluding in combination a shank end portion and a cutting end portion,said cutting end portion comprising a plurality of teeth extending in ahelical direction at a given helix angle, each said tooth having acutting face side, a trailing side and a land surface connecting the twoaforementioned sides, said cutting face side having a constant positiveradial rake relationship with the end mill axis, the intersection ofsaid cutting face side and said land surface comprising the cutting edgeof said tooth, said cutting edge being continuous substantially theentire length thereof, wall means on said cutting face side of saidtooth defining a plurality of axially spaced high areas and low areaswhen viewed in the radial direction of the end mill, said land surfaceextending in a manner to provide cutting relief for said cutting edge.

15. An end mill as claimed in claim 14, wherein said high areas and lowareas start a given spaced axial distance from the extreme forward axialend of said tooth with said tooth for said given spaced axial distancebeing of conventional construction, said given space distance being onthe order of at least one-sixteenth of the outside diameter of saidcutting portion.

16. An end mill as claimed in claim 15, wherein said given axialdistance is on the order of at least oneeighth of the outside diameterof said cutting end portion.

17. An end mill as claimed in claim 14, wherein said high and low areasare generally sinusoidal in configuration.

18. An end mill as claimed in claim 17, wherein said cutting edge whenviewed in a direction generally at a right angle to said radialdirection defining high areas and low areas which are generallysinusoidal in configuration.

19. An end mill as claimed in claim 14, wherein said high areas aresubstantially flat on top.

20. An end mill as claimed in claim 19, wherein said cutting edge whenviewed in a direction generally at a right angle to said radialdirection defining another curve with high areas and low areas with saidhigh areas being substantially flat on top.

21. An end mill as claimed in claim 17, wherein said cutting edge whenviewed in a direction generally at a right angle to said radialdirection defines substantially a straight line.

22. An end mill as claimed in claim 21, wherein said straight line issubstantially parallel to the axis of the end mill.

23. A rotating cutting tool having an improved cutting action comprisinga cutting portion, said cutting portion having a plurality of spacedcutting edges, each of said spaced cutting edges following the path of acurve which defines alternate peaks and valleys, each of said peakscomprising a surface which is substantially flat, the depth from a peakto a valley being small as compared to the pitch distance betweenadjacent peaks.

24. A tool as claimed in claim 23, wherein said cutting edges arecircumferentially spaced and helically extending.

25. A tool as claimed in claim 23, wherein said flat surface issubstantially parallel with the axis of the tool.

26. A tool as claimed in claim 13, wherein said flat surface of a peakon one cutting edge is axially offset from a corresponding flat surfaceof a peak on an adjacent cutting edge.

27. A tool as claimed in claim 26, wherein the axial distance of a flatsurface multiplied by the number of cutting edges is at least as greatas said pitch distance.

28. A milling cutter as claimed in claim 7, wherein each of said cuttingedges follows the path of a curve which defines alternate peaks andvalleys, each of said peaks comprising a surface which is substantiallyflat, the depth from a peak to a valley being small as compared to thepitch distance between adjacent peaks.

29. A tool as claimed in claim 28, wherein said cutting edges arecircumferentially spaced and helically extending.

30. A tool as claimed in claim 28, wherein said flat surface of a peakon one cutting edge is axially offset from a corresponding flat surfaceof a peak on an adjacent cutting edge.

31. A tool as claimed in claim 30, wherein the axial distance of a flatsurface multiplied by the number of cutting edges is at least as greatas said pitch distance.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION .Patent No. 3,775819 Dated December 4, 1973 Inventor s Thomas A, Ribich bove-identifiedpatent It is certified that error appears in the a d as shown below:

and that said Letters'Patentare hereby correcte In Claim 26, Column' 10,line 29, "13" should read "23 Signed and sealed this 17th day ofSeptember 1974.

(SEAL) Attest:

MCCQY M. GIBSON JR C MARSHAL o L DANN Attesting Officer Commissioner ofPatents USCOMM-DC 608764 69 \LS. GOVERNMENT PRINTING OFFICE: I9890-366-334,

FORM po-wsono-ss)

1. A milling cutter blank having an axis and including in combination acutting portion, said cutting portion comprising a plurality of teeth,each said tooth having a cutting face side, a trailing side, and a landsurface connecting the two aforementioned sides, said cutting face sidehaving a constant positive radial rake relationship with the cutteraxis, wall means on said cutting face side of said tooth defining aplurality of axially spaced indentations which are recessed toward saidtrailing side from a reference line at said cutting face side which lineextends generally parallel to said tooth.
 2. A milling cutter blank asclaimed in claim 1, wherein said axially spaced indentations on saidcutting face side of said tooth start at a given spaced axial distancefrom the extreme forward axial end of said tooth with said tooth forsaid given spaced axial distance being of conventional unindentedconstruction, said given spaced axial distance being on the order of atleast one-sixteenth of the outside diameteR of said cutting portion. 3.A milling cutter blank as claimed in claim 2, wherein said given spacedaxial distance is on the order of at least one-eighth the outsidediameter of said cutting portion.
 4. A milling cutter blank as claimedin claim 1, wherein said teeth extend in a helical direction at a givenhelix angle.
 5. A milling cutter blank as claimed in claim 1, whereinsaid land surface is formed as an arc of a circle.
 6. A milling cutterblank as claimed in claim 4, wherein said cutter blank is an end millblank with a shank end portion connected to said cutting portion.
 7. Amilling cutter having an axis and having an improved cutting actionincluding in combination a cutting portion, said cutting portioncomprising a plurality of teeth extending in generally an axialdirection, each said tooth having a cutting face side, a trailing side,and a land surface connecting the two aforementioned sides, said cuttingface side having a constant positive radial rake relationship with thecutter axis, the intersection of said cutting face side and said landsurface defining a cutting edge which is continuous substantially theentire axial length of said tooth, said land surface being relieved fromsaid cutting face side in the direction of said trailing side, wallmeans on said cutting face side of said tooth defining a plurality ofaxially spaced indentations which are recessed toward said trailingside.
 8. A milling cutter as claimed in claim 7, wherein said wall meanswhich define said plurality of axially spaced indentations also define aplurality of axially spaced high areas and low areas when viewed in theradial direction of the milling cutter.
 9. A milling cutter as claimedin claim 8, wherein said cutting edge when viewed in a directiongenerally at a right angle to said radial direction defines a pluralityof connected curves having alternately high areas and low areas.
 10. Amilling cutter as claimed in claim 9, wherein said last mentioned highareas are generally flat on top.
 11. A milling cutter as claimed inclaim 8, wherein said cutting edge when viewed in a direction generallyat a right angle to said radial direction defines substantially astraight line.
 12. A milling cutter as claimed in claim 7, wherein saidaxially spaced indentations on said cutting face side of said toothstart at a given spaced axial distance from the extreme axial forwardend of said tooth with said tooth for said given spaced axial distancebeing of conventional nonindented construction, said given spaced axialdistance being on the order of at least one-sixteenth of the outsidediameter of said cutting portion.
 13. A milling cutter as claimed inclaim 12, wherein said given spaced axial distance is on the order of atleast one-eighth of the outside diameter of said cutting portion.
 14. Anend mill having an axis and having an improved cutting action includingin combination a shank end portion and a cutting end portion, saidcutting end portion comprising a plurality of teeth extending in ahelical direction at a given helix angle, each said tooth having acutting face side, a trailing side and a land surface connecting the twoaforementioned sides, said cutting face side having a constant positiveradial rake relationship with the end mill axis, the intersection ofsaid cutting face side and said land surface comprising the cutting edgeof said tooth, said cutting edge being continuous substantially theentire length thereof, wall means on said cutting face side of saidtooth defining a plurality of axially spaced high areas and low areaswhen viewed in the radial direction of the end mill, said land surfaceextending in a manner to provide cutting relief for said cutting edge.15. An end mill as claimed in claim 14, wherein said high areas and lowareas start a given spaced axial distance from the extreme forward axialend of said tooth with said tooth for said given spaced axial distancebeing of conventional construction, said given spaCe distance being onthe order of at least one-sixteenth of the outside diameter of saidcutting portion.
 16. An end mill as claimed in claim 15, wherein saidgiven axial distance is on the order of at least one-eighth of theoutside diameter of said cutting end portion.
 17. An end mill as claimedin claim 14, wherein said high and low areas are generally sinusoidal inconfiguration.
 18. An end mill as claimed in claim 17, wherein saidcutting edge when viewed in a direction generally at a right angle tosaid radial direction defining high areas and low areas which aregenerally sinusoidal in configuration.
 19. An end mill as claimed inclaim 14, wherein said high areas are substantially flat on top.
 20. Anend mill as claimed in claim 19, wherein said cutting edge when viewedin a direction generally at a right angle to said radial directiondefining another curve with high areas and low areas with said highareas being substantially flat on top.
 21. An end mill as claimed inclaim 17, wherein said cutting edge when viewed in a direction generallyat a right angle to said radial direction defines substantially astraight line.
 22. An end mill as claimed in claim 21, wherein saidstraight line is substantially parallel to the axis of the end mill. 23.A rotating cutting tool having an improved cutting action comprising acutting portion, said cutting portion having a plurality of spacedcutting edges, each of said spaced cutting edges following the path of acurve which defines alternate peaks and valleys, each of said peakscomprising a surface which is substantially flat, the depth from a peakto a valley being small as compared to the pitch distance betweenadjacent peaks.
 24. A tool as claimed in claim 23, wherein said cuttingedges are circumferentially spaced and helically extending.
 25. A toolas claimed in claim 23, wherein said flat surface is substantiallyparallel with the axis of the tool.
 26. A tool as claimed in claim 13,wherein said flat surface of a peak on one cutting edge is axiallyoffset from a corresponding flat surface of a peak on an adjacentcutting edge.
 27. A tool as claimed in claim 26, wherein the axialdistance of a flat surface multiplied by the number of cutting edges isat least as great as said pitch distance.
 28. A milling cutter asclaimed in claim 7, wherein each of said cutting edges follows the pathof a curve which defines alternate peaks and valleys, each of said peakscomprising a surface which is substantially flat, the depth from a peakto a valley being small as compared to the pitch distance betweenadjacent peaks.
 29. A tool as claimed in claim 28, wherein said cuttingedges are circumferentially spaced and helically extending.
 30. A toolas claimed in claim 28, wherein said flat surface of a peak on onecutting edge is axially offset from a corresponding flat surface of apeak on an adjacent cutting edge.
 31. A tool as claimed in claim 30,wherein the axial distance of a flat surface multiplied by the number ofcutting edges is at least as great as said pitch distance.